Polymer foam and method for preparing the same

Abstract

Polymer foam and a method for preparing the same are disclosed. In the present disclosure, the method sequentially comprises the following steps: providing a polymer body; performing a pressure-induced flow (PIF) process on the polymer body at a first predetermined temperature and a first predetermined pressure for a pressure holding time, to obtain a polymer sheet; and performing a foaming process on the polymer sheet by using a foaming agent at a second predetermined temperature and a second predetermined pressure for a saturation time, to obtain polymer foam.

Description

CROSS REFERENCE TO RELATED APPLICATION[0001]This application claims the benefit of filing date of U.S. Provisional Application Ser. No. 62 / 197,630, entitled “Semi-crystalline Polymer Nanocomposite and Foam Structure and Method for Making the Same” filed Jul. 28, 2015 under 35 USC §119(e)(1).BACKGROUND[0002]1. Field of the Invention[0003]The present disclosure relates to a method for preparing polymer foam and, more particularly to a method for preparing polymer foam via a pressure-induced flow (PIF) process.[0004]2. Description of Related Art[0005]Polymer foam, especially polypropylene foam, has many industrial applications, and the global polymer foam market has witnessed a rapid growth in the past few years.[0006]Polypropylene (PP), as one of the most widely used commercial polymers, has many desirable properties, such as high melting point, good plasticity, low density, excellent chemical resistance and food safety, and easy recycling. These outstanding properties as well as a lo...

AI Technical Summary

Benefits of technology

The present patent provides a method for preparing a polymer sheet or foam with a co-continuous structure, which has superior mechanical and physical properties compared to conventional composites and foams made by the same composition. The method involves coating materials onto polymer pellets and then performing a PIF process at a high temperature and pressure for a specific holding time to obtain a polymer sheet with a co-continuous structure. The resulting polymer sheet or foam can then be treated with a foaming process using a foaming agent at a lower temperature and pressure for a saturation time to obtain a low-density foam with high performance. This method is more suitable for industrial applications due to the reduced pressure and time required. Additionally, the resulting polymer foam has low foam density and high strength, making it useful in various industrial applications.

Problems solved by technology

However, like other commodity polymers, the low thermal stability and mechanical strength prevent PP from many engineering and structural applications.

Furthermore, its low melt strength leads to cell rupture and low expansion ratio in the melt foaming process unless long-chain branching, polymer compounding, or chemical crosslinking are used to modify PP.

However, PP is very difficult to be foamed because of its low melt strength and high crystallinity.

However, these methods face limited applications owning to the significant cost increase in materials and poor mechanical strength of foamed products in comparison with PP and other widely used foam materials such as polystyrene (PS).

It is known that the unmodified polymer, especially neat polypropylene (PP), is very difficult to be foamed due to its low melt strength and high crystallinity.

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